The molecular chaperone DnaJ is required for the degradation of a soluble abnormal protein in Escherichia coli

被引:50
作者
Huang, HC [1 ]
Sherman, MY [1 ]
Kandror, O [1 ]
Goldberg, AL [1 ]
机构
[1] Harvard Univ, Sch Med, Dept Cell Biol, Boston, MA 02115 USA
关键词
D O I
10.1074/jbc.M002937200
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
In addition to promoting protein folding and translocation, molecular chaperones of Hsp70/DnaJ families are essential for the selective breakdown of many unfolded proteins. It has been proposed that chaperones function in degradation to maintain the substrates in a soluble form. In Escherichia coli, a nonsecreted alkaline phosphatase mutant that lacks its signal sequence (PhoA Delta2-22) fails to fold in the cytosol and is rapidly degraded at 37 degreesC. We show that PhoA Delta2-22 is degraded by two ATP-dependent proteases, La (Lon) and ClpAP, and breakdown by both is blocked in a dnaJ259-ts mutant at 37 degreesC. Both proteases could be immunoprecipitated with PhoA, but to a much lesser extent in the dnaJ mutant. Therefore, DnaJ appears to promote formation of protease-substrate complexes. DnaJ could be coimmunoprecipitated with PhoA, and the extent of this association directly correlated with its rate of degradation. Although PhoA was not degraded when DnaJ was inactivated, 50% or more of the PhoA remained soluble. PhoA breakdown and solubility did not require ClpB. PhoA degradation was reduced in a thioredoxin-reductase mutant (trxB), which allowed PhoA Delta2-22 to fold into an active form in the cytosol. Introduction of the dnaJ mutation into trxB cells further stabilized PhoA, increased enzyme activity, and left PhoA completely soluble. Thus, DnaJ, although not necessary for folding (or preventing PhoA aggregation), is required for PhoA degradation and must play an active role in this process beyond maintaining the substrate in a soluble form.
引用
收藏
页码:3920 / 3928
页数:9
相关论文
共 51 条
  • [1] Cheetham ME, 1998, CELL STRESS CHAPERON, V3, P28, DOI 10.1379/1466-1268(1998)003<0028:SFAEOD>2.3.CO
  • [2] 2
  • [3] A NOVEL FUNCTION OF ESCHERICHIA-COLI CHAPERONE DNAJ - PROTEIN-DISULFIDE ISOMERASE
    DECROUYCHANEL, A
    KOHIYAMA, M
    RICHARME, G
    [J]. JOURNAL OF BIOLOGICAL CHEMISTRY, 1995, 270 (39) : 22669 - 22672
  • [4] A SIGNAL SEQUENCE IS NOT REQUIRED FOR PROTEIN EXPORT IN PRLA MUTANTS OF ESCHERICHIA-COLI
    DERMAN, AI
    PUZISS, JW
    BASSFORD, PJ
    BECKWITH, J
    [J]. EMBO JOURNAL, 1993, 12 (03) : 879 - 888
  • [5] ESCHERICHIA-COLI ALKALINE-PHOSPHATASE FAILS TO ACQUIRE DISULFIDE BONDS WHEN RETAINED IN THE CYTOPLASM
    DERMAN, AI
    BECKWITH, J
    [J]. JOURNAL OF BACTERIOLOGY, 1991, 173 (23) : 7719 - 7722
  • [6] MUTATIONS THAT ALLOW DISULFIDE BOND FORMATION IN THE CYTOPLASM OF ESCHERICHIA-COLI
    DERMAN, AI
    PRINZ, WA
    BELIN, D
    BECKWITH, J
    [J]. SCIENCE, 1993, 262 (5140) : 1744 - 1747
  • [7] Chaperone-mediated protein folding
    Fink, AL
    [J]. PHYSIOLOGICAL REVIEWS, 1999, 79 (02) : 425 - 449
  • [8] PEPTIDE-BINDING SPECIFICITY OF THE MOLECULAR CHAPERONE BIP
    FLYNN, GC
    POHL, J
    FLOCCO, MT
    ROTHMAN, JE
    [J]. NATURE, 1991, 353 (6346) : 726 - 730
  • [9] PROTEIN FOLDING IN THE CELL
    GETHING, MJ
    SAMBROOK, J
    [J]. NATURE, 1992, 355 (6355) : 33 - 45
  • [10] Hsp104, Hsp70, and Hsp40: A novel chaperone system that rescues previously aggregated proteins
    Glover, JR
    Lindquist, S
    [J]. CELL, 1998, 94 (01) : 73 - 82